modem

The modern human’s worst nightmare: a power outage. Left without cat memes, Netflix, and — of course — Hackaday, there’s little to do except participate in the temporary anarchy that occurs when left without internet access. Lamenting over expensive and bulky uninterruptible power supplies, Youtube user [Gadget Addict] hacked together a UPS power bank that might just stave off the collapse of order in your household.

This simple and functional hack really amounts to snipping the end off of a USB power cable. The cable is then attached to a screw terminal to barrel connector adapter and plugged it into a pass-through power USB power bank. No, really — that’s all there is to it. [Gadget Addict] notes that while most modems and routers are designed to run off a 12V power supply, they still operate at 5V. He goes on to connect several router and router/modem combination units to the power bank. In each case the system appears to boot up and perform normally.

Before modern CRTs with ancient VGA connectors, and before fancy video terminals, the display for computers large and slightly smaller was the Teletype. While many of these Teletypes were connected directly, they were designed to be a remote terminal, connected through Ma Bell’s network. [NeXT] over on the Vintage Computer Forums is bringing the iconic ASR33 Teletype into the 21st century by giving this old display a modern way to connect to the outside world.

If you ever see a Teletype in action, it will be connected to a local machine. This was certainly not always the case. The Teletype was designed to connect to remote systems. [NeXT]’s Teletype came with a Call Control Unit designed for Telex lines, which do not exist anymore. Modems for the ASR33 existed, but good luck finding one. Lucky for [NeXT], nearly every modem ever made is backwards-compatible with the Bell Dataphone, one of the standard ways of plugging a Teletype into a phone line. All [NeXT] had to do was put a modem inside this Teletype.

With relays, transistors, LEDs, and a lot of perfboard, [NeXT] successfully built a circuit that would interface the Teletype’s Call Control Unit to a Hayes Smartmodem tucked away inside the stand. Believe it or not, this is an exceptionally useful build; if you ever find a Teletype tucked away in the back of an old office, in a surplus shop, or on Craigslist, odds are it won’t be compatible with any modern electronics. That’s not to say land lines are particularly modern, but since there’s a microcontroller included in the new circuitry, it’s relatively easy to add a USB port to this ancient terminal.

Readers of a certain age will remember the payphone trick of letting the phone ring once and then hanging up to get your quarter back. This technique was used with a pre-planned call time to let someone know you made it or you were okay without accruing the cost of a telephone call. As long as nobody answered you didn’t have to pay for the call, and that continues to be the case with some pay-per-minute cellphone plans.

This is the concept behind [Antonio Ospite’s] ringtone data transfer project called SaveMySugar. Don’t judge him, this work has been ongoing for around ten years and started back when cellphone minutes were a concern. We’re just excited to see that he got the excruciatingly slow thing to work.

Those wanting to dig down to the nitty-gritty of the protocol (and you should be one of them) will want to read through the main project page. The system works by dialing the cellphone, letting it ring once, then hanging up. The time between redials determines a Morse code dot, dash, or separation between characters. Because you can’t precisely determine how long it will take each connection to read, [Antonio] built ‘noise’ measurement into the system to normalize variations. The resulting data transfer works quite well. He was able to transfer the word “CODEX” in just six minutes and thirty seconds. But it is automatic, so what do you care? See the edge-of-your-seat-action play out in the video below.

If there’s any indication of the Commodore 64’s longevity, it’s the number of peripherals and add-ons that are still being designed and built. Right now, you can add an SD card to a C64, a technology that was introduced sixteen years after the release of the Commodore 64. Thanks to [Leif Bloomquist], you can also add WiFi to the most cherished of the home computers.

[Leif]’s WiFi modem for the C64 is made of two major components. The first is a Microview OLED display that allows the user to add SSIDs, passwords, and configure the network over USB. The second large module is the a Roving Networks ‘WiFly’ adapter. It’s a WiFi adapter that uses the familiar Xbee pinout, making this not just a WiFi adapter for the C64, but an adapter for just about every wireless networking protocol out there.

[Leif] introduced this WiFi modem for the C64 at the World of Commodore earlier this month in Toronto. There, it garnered a lot of attention from the Commodore aficionados and one was able to do a video review of the hardware. You can check out [Alterus] loading up a BBS over Wifi in the video below.

The headphones couple audio tones to [Canny’s] microphone using AFSK (audio frequency shift keying). [Canny] uses an opamp to bring the microphone level up and then uses a 567 PLL IC to decode the audio tones. [Adam] selected two clever frequencies for the mark and space (12345 Hz and 9876 Hz). In addition to being numerically entertaining, the frequencies are far enough apart to be easy to detect, pass through the headphones with no problem, and are not harmonically related.

In the old days, a serial port often connected to an acoustic coupler that gripped a phone handset and allowed a remote connection to a far away serial port (via another phone and acoustic coupler) at a blistering 300 baud or less. The acoustic coupler would do the job of converting serial data to audio and reconstituting it after its trip through the phone lines. Modems advanced, but have mostly given way to DSL, Cable, Fiber, and other high speed networking options.

In a decidedly retro move, [James Halliday] and [jerky] put a modern spin on that old idea. They used the webaudio API to send serial data to a remote Arduino. The hack uses a FET, a capacitor, and a few resistors. They didn’t quite build a real modem with the audio. Instead, they basically spoof the audio port into sending serial data and recover it with the external circuitry. They also only implement serial sending (so the Arduino receives) so far, although they mention the next step would be to build the other side of the connection.

[Maurice] recently built a clock that draws the time (Google Doc) on a white board. We’ve seen plenty of clock hacks in the past, and even a very similar one. It’s always fun to see the different creative solutions people can come up with to solve the same problem.

This device runs on a PIC16F1454 microcontroller. The code for the project is available on GitHub. The micro is also connected to a 433MHz receiver. This allows a PC to keep track of the time, instead of having to include a real-time clock in the circuit. The USB connector is only used for power. All of the mounting pieces were designed in OpenSCAD and printed on a 3D printer. Two servos control the drawing arms. A third servo can raise and lower the marker to the whiteboard. This also has the added benefit of being able to place the marker tip inside of an eraser head. That way the same two servos can also erase the writing.

The communication protocol for this systems is interesting. The transmitter shows up on [Maurice’s] PC as a modem. All he needs to do to update the time is “echo 12:00 > /dev/whiteboard”. In this case, the command is run by a cron job every 5 minutes. This makes it easy to tweak the rate at which the time updates on the whiteboard. All communication is done one-way. The drawing circuit will verify the checksum each time it receives a message. If the check fails, the circuit simply waits for another message. The computer transmits the message multiple times, just in case there is a problem during transmission.